After Victor Francis Hess's discovery of cosmic radiation, physicist Bruno Rossi researched the nature of these rays. He proposed a system of arranging Geiger counters to determine the positive or negative charge of particles coming from outer space. He discovered Sco X-1, the first extra-solar source of x-rays; developed the Rossi curve, a means of observing simultaneous occurrence of three or more electrical pulses using juxtaposed Geiger counters; and discovered the magnetopause, the boundary in space where Earth's magnetic field loses its dominance. Forced to leave fascist Italy, Rossi eventually came to the United States, where he was involved in the development of advanced radar, studied X-ray astronomy and space plasma physics, worked on America's Manhattan Project developing atomic weapons, and pioneered the developing field for high-energy particle physics. He is the namesake of the Bruno Rossi Prize, awarded by the American Astronomical Society for achievement in high energy astrophysics.